I actually have one of each, though I haven't used the chin spin yet cause my youngest is under 6 months. My chins LOVE the flying saucer, though it took one a few weeks to understand what it was and how to use it. He figured out how to use it first and then the other kept sitting on it and swaying back and forth until he eventually got the hang of it and now they both switch off using it ALL the time. It is really quiet, the only thing that makes noise is the doors of my ferret nation clanging in the holes. To prevent that, I took scraps of fleece and folded them up thick and put them in the top and bottom of each door to hold them steady while they run. Now it is basically silent.
Next, I added in the silver surfer. They immediately figured out how to run on that one and loved it. It hooks on to a cross bar and then screws tight onto two lower upright bars. The two hooks have no padding between them and the bar so when they run it would clang pretty loudly. To fix that I took very small strips of fleece and pulled them up under the hooks and wrapped them between the hooks and the bar a few times. Then I pulled a folded in half patch of fleece and maneuvered it behind the whole back panel in front of the cage bars. Now that one is also completely silent.
I think both wheels are great, my chins use both non stop. The silver surfer is easier to put on but the flying saucer is not too difficult either. You can't really go wrong either way!